Amendment 4 of 27 · Bill of Rights · 1791
Fourth Amendment
Search and seizure
The one-line version
Police generally need a warrant, your consent, or a legal exception to search you, your home, your phone, or your things.
The Fourth Amendment in plain English
You have the right to be secure in your body, your home, your belongings, and your communications, and the government cannot search or take them unreasonably. The government cannot get a warrant unless it has good reason to believe a crime is involved, swears to that reason under oath, and describes specifically what will be searched and what will be taken.
Original text, 1791
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
Phrase by phrase
The right of the people to be secure in their persons, houses, papers, and effects
- You, your home, your documents, and your belongings are protected.
against unreasonable searches and seizures, shall not be violated
- The government cannot search you or take your things without a good legal reason.
no Warrants shall issue, but upon probable cause
- A judge can approve a warrant only when there is good reason to believe evidence of a crime will be found.
supported by Oath or affirmation
- The officer asking for the warrant must swear the reasons are true.
particularly describing the place to be searched, and the persons or things to be seized
- The warrant must say exactly where police can search and what they can take.
Picture it
Example. Not legal advice.
You're walking home and an officer asks, "Mind if I look in your backpack?" You can say, "I don't consent to searches." If the officer searches anyway, do not physically resist. Remember what happened and tell a lawyer later.
What this means for you
Three ways police can search
Police can search you, your phone, your car, your home, your bag, or your mail in three main ways. They can get a warrant from a judge. They can get your consent. Or they can use a recognized legal exception.
Many searches happen because someone said yes. If an officer asks "Can I search your bag?" and you freely agree, the search is generally legal.
Your right to say no
You can refuse consent. Say it calmly and clearly: "I do not consent to this search."
Refusing is not a crime. Do not physically resist if an officer searches anyway. Whether that search was legal is a question for a court later, not for you in the moment.
Phones
Since Riley v. California (2014), police generally need a warrant to search your phone, even after an arrest. They can ask for your passcode, and you can decline to answer questions. Whether a court can order you to unlock your phone is still debated.
Cars
Police can search a car without a warrant if they have probable cause, meaning good reason to believe it holds evidence of a crime. They can also ask to search. You can say no.
At school
Public school officials can search students with "reasonable suspicion," a lower standard than police need. This can cover lockers, backpacks, and sometimes phones, depending on your state. Private schools are not the government, so the Fourth Amendment does not apply to them.
Myth check
MythIf I refuse a search, it shows I'm hiding something.
FactSaying no is your right. Refusing is not a crime, and courts have said it is not, by itself, a reason to search you.
MythOnce I'm arrested, police can go through my phone.
FactSince Riley v. California (2014), police generally need a warrant to search your phone, even after an arrest.
MythThe Fourth Amendment protects me from my boss or a store.
FactIt limits the government, including police and public schools. It does not apply to private companies, stores, or employers.
Common questions
What does the Fourth Amendment say in simple terms?
It means the government cannot search you or take your things without a good legal reason. Police generally need a warrant, your consent, or a legal exception to search you, your home, your phone, or your belongings.
Can police search my phone without a warrant?
Generally, no. In Riley v. California (2014), the Supreme Court said police usually need a warrant to search a phone, even after an arrest. There are narrow emergency exceptions.
Can police search my car without a warrant?
Sometimes. If police have probable cause, meaning good reason to believe the car holds evidence of a crime, they can generally search it without a warrant. The Supreme Court allowed this in Carroll v. United States (1925). Police can also search if you consent.
Can I say no to a police search?
Yes. You can refuse to consent to a search. Consent is one exception to the warrant rule, so agreeing generally makes a search legal. In Schneckloth v. Bustamonte (1973), the Supreme Court said police do not have to tell you that you can refuse. Police may still search with a warrant or another exception.
Can my school search my backpack?
Yes, if officials have reasonable suspicion. In New Jersey v. T.L.O. (1985), the Supreme Court said public school officials need reasonable suspicion, a lower standard than the probable cause police need. The search must also fit its purpose. Private schools are not bound by the Fourth Amendment.
What happens if police search me illegally?
Evidence from an illegal search generally cannot be used against you at a criminal trial. This is called the exclusionary rule. The Supreme Court applied it to state courts in Mapp v. Ohio (1961). There are exceptions, such as when police relied in good faith on a warrant.
Go deeper
The scene · 1791
Before the Revolution, British customs officers carried "writs of assistance." These were blanket warrants that let them search any home or shop, any time, for anything. In 1761 a Boston lawyer named James Otis argued in court that these warrants destroyed people's freedom. Thirty years later, the Fourth Amendment banned them.
Back then
Americans remembered soldiers and customs officers searching homes with no limits. The writers wanted a neutral judge to stand between the police and your front door. That is why the amendment puts so many conditions on warrants.
Words that changed
- “papers”
ThenPrivate letters, diaries, and business records.
NowCourts now protect some digital records too, including the contents of your phone and your past cell phone location records.
- “effects”
ThenYour personal belongings.
NowStill your belongings: your bag, your car, your phone.
- “seizure”
ThenTaking a person or their property.
NowBeing stopped and held by police counts as a seizure of you, even for a few minutes.
Key cases
- 1961
Mapp v. Ohio
Evidence found in an illegal search generally cannot be used against you in a state criminal trial.
- 1968
Terry v. Ohio
Police can briefly stop and pat down a person if they have reasonable suspicion of a crime and a reason to think the person is armed.
- 1985
New Jersey v. T.L.O.
Public school officials can search a student with reasonable suspicion, a lower standard than police need.
- 2014
Riley v. California
Police generally need a warrant to search the phone of someone they arrest.
- 2018
Carpenter v. United States
Police generally need a warrant to get your cell phone location records from your phone company.
More history and context
The Fourth Amendment was ratified in 1791. At first it limited only the federal government. Through the Fourteenth Amendment, it now limits every level of government: federal, state, county, and city.
In 1791, "papers" meant private letters, journals, and documents. Courts have extended this protection to phone contents, emails, texts, and location data. The plain-English version says "communications" for "papers" because that is what the modern protection covers.
The word "unreasonable" is the center of the amendment. For more than two centuries, courts have decided what makes a search reasonable: what counts as probable cause, which exceptions exist, and what the rules are at borders, in cars, at schools, and at work. The Supreme Court hears new cases about it almost every year. The protection in the text is broad. In practice, it depends on what courts are saying now.
Actively contested
Courts are still deciding parts of this. Open questions include:
- Digital privacy and the third-party doctrine
- Searches of phones and laptops at the border
- School and workplace search standards
Quick check
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